According to fifth and sixth embodiments of Patent Literature 1 below, a construction method for a foundation pile is disclosed, in which a cylindrical body formed of a carbon fiber sheet is suspended and moved down into a borehole formed on the ground, and concrete is poured into the suspended cylindrical body, and the poured concrete is integrated with the cylindrical body to form the foundation pile.
Further, according to the same Patent Literature, the cylindrical body may be formed in a bag-like shape by closing a bottom portion of the cylindrical body, but the Patent Literature merely discloses that the concrete is poured while supporting the bottom portion of the cylindrical body with a bottom surface of the borehole. Basically, this technology is based on a technical idea of pouring the concrete into the cylindrical body including both a top end and a bottom end opened.